Intravenous (IV) therapy is a versatile technique used for the administration of medical fluids to and withdrawal of bodily fluids from patients. IV therapy has been used for various purposes such as the maintenance of fluid and electrolyte balance, the transfusion of blood, the administration of nutritional supplements, chemotherapy, and the administration of drugs and medications. Fluids may be administered intravenously by injection through a hypodermic needle, or intermittently or continuously by infusion using a needle or catheter. The most common intravenous access method utilized by clinicians is the peripheral IV catheter.
A peripheral IV catheter is made of soft, flexible plastic or silicone, generally between fourteen to twenty-four gauge in size. In the conventional venipuncture procedure, a catheter is inserted into a vein in the patient's hand, foot, or the inner aspect of the arm or any vein in the body that will accept an IV catheter. In order to properly place the IV catheter into a patient's vein, a sharp introducer needle must be used to puncture the skin, tissue, and vein wall to provide a path for placement of the catheter into the vein.
Referring to FIGS. 1 and 2, a conventional IV safety needle assembly 20 configured for insertion of an “over-the needle” catheter 22 is depicted. The catheter 22 is operably coupleable to the safety needle assembly 20, in part by positioning the catheter 22 coaxially over the needle 24 of the safety needle assembly 20. The catheter 22 thus rides with the needle 24 through the skin, tissue, and vein wall and into the patient's vein. Often, the insertion end of the catheter 22 is tapered in an effort to minimize the amount of force required to insert catheter 22 into the biological site.
The catheter 22 can include a catheter hub 30, which can be selectively coupled to a portion of the safety needle assembly 20. Catheter hub 30 is sometimes configured to control the flow of fluid through catheter 22 via an internal fluid passageway that runs substantially parallel to the longitudinal axis of catheter hub 30. In some embodiments, the fluid passageway includes a septum or valve to enable sealing of the fluid passageway to restrict or prevent bodily fluid from leaking out of catheter hub 30 when catheter 22 is inserted into a patient's vein and the needle 24 is removed. Various catheter hub designs having a septum and/or valve are disclosed in a concurrently filed application entitled “Intravenous Catheter Assembly Design,” Ser. No. 15/011,981, which is incorporated by reference herein.
When the needle 24 pierces the vein, blood will “flashback” through the needle 24 and into the flashback chamber 26. Thus, once the clinician observes this flashback of blood, the clinician will know that the catheter 22 and needle 24 have been inserted in the vein. The catheter 22 can be advanced further into the vein as desired and needle 24 can then be withdrawn from the catheter 22.
In addition to placement of an IV catheter, it is frequently necessary for a sample of the patient's blood to be obtained (e.g., for testing, blood typing or other analysis of a patient's condition). Such analysis frequently involves testing the blood for the presence of certain characteristics, such as the presence or amount of one or more constituents, or to determine the level of one or more than one parameter. For many of these blood tests, only a small sample of blood is required. After the IV catheter has been inserted, the clinician may obtain a blood sample through a variety of methods. One method is to have the patient endure another needle stick either by a needle and syringe to draw an aliquot of blood, or by pricking the patient's finger with a lancet for a few drops of blood.
Because some IV catheters of the prior art include an integrated flash chamber 26, another method is to enable access to the blood within the flash chamber 26 after the catheter 22 and needle 24 have been inserted into the patient's vein. Usually the proximal end of the flash chamber 26 is blocked by a flash plug 28. The flash plug 28 typically includes a filter material that enables air to vent from the flash chamber as the blood or fluid fills the chamber, but inhibits the blood or fluid from passing from the flash chamber 26.
In some IV catheters, the flash plug 28 is removable. Examples of catheter insertion devices incorporating removable plugs are marketed by Smiths Medical ASD, Inc. of St. Paul, Minn., under the JELCO and INTUITIV Safety IV Catheters trademarks, as described by U.S. Pat. Nos. 7,291,130 and 8,257,322, both of which are incorporated by reference herein. With this type of catheter, removal of the flash plug 28 opens the flash chamber 26, thereby providing access to the blood within the flash chamber 26 for testing. Although advantageous in some regards, this action has the potential to expose clinicians to hazardous material if improperly handled, such as blood or other bodily fluid that may spill from the flash chamber 26 as the plug 28 is removed.
In other IV catheters of the prior art, the flash plug 28 is fixed or non-removable. Examples of catheter insertion devices incorporating non-removable plugs are described in U.S. Pat. No. 5,000,740 (depicting an IV catheter insertion device marketed by Smiths Medical ASD, Inc. under the PROTECTIV trademark) and U.S. Pat. No. 7,736,342 (depicting an IV catheter insertion device marketed by Smiths Medical ASD, Inc. under the VIAVALVE trademark), both of which are incorporated by reference herein.
With non-removable flash plugs 28, clinicians must adapt special methods if they wish to access the blood within the flash chamber 26. One such method to access blood with a non-removable flash plug involves finding and using an external probe, such as a pen, to push the flash plug 28 within the flash chamber 26 to expel blood from the flash chamber 26 through the needle 24. The use of an external device such as a pen can be undesirable for several reasons. In particular, it is cumbersome in that it requires that the clinician find a pen or similar object, and use both hands to access the blood within the flash chamber 26. It increases the risk that the pen or other object, which may not be sterile, if improperly handled, will contaminate the blood and cause inaccuracies in the following tests. And, if improperly handled, it increases the risk that the pen itself will become contaminated from the blood within flash chamber 26, thereby putting the clinician and other patients at risk of making contact with trace amounts of the blood.
Accordingly, the applicants have identified a need for a better way of accessing and testing fluid trapped in a flashback chamber of a needle assembly in a manner that reduces the risk of the fluid spilling, while reducing the possibility of an inadvertent needle stick.